An analysis of crop yields for the state of Missouri was completed to determine if an interannual or multidecadal variability existed as a result of the El Niño Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO). Corn and soybean yields were recorded in kilograms per hectare for each of the six climate regions of Missouri. An analysis using the Mokhov "method of cycles" demonstrated interannual, interdecadal, and multidecadal variations in crop yields. Cross-spectral analysis was used to determine which region was most impacted by ENSO and PDO influenced seasonal (April-September) temperature and precipitation. Interannual (multidecadal) variations found in the spectral analysis represent a relationship to ENSO (PDO) phase, while interdecadal variations represent a possible interaction between ENSO and PDO. Average crop yields were then calculated for each combination of ENSO and PDO phase, displaying a pronounced increase in corn and soybean yields when ENSO is warm and PDO is positive. Climate regions 1, 2, 4, and 6 displayed significant differences (p value of 0.10 or less) in yields between El Niño and La Niña years, representing 55-70 % of Missouri soybean and corn productivity, respectively. Final results give the opportunity to produce seasonal predictions of corn and soybean yields, specific to each climate region in Missouri, based on the combination of ENSO and PDO phases.
Changes in the general circulation of the atmosphere have been taking place during the latter part of the twentieth century and the early part of the twenty-first century. In the Belgorod region of Southwest Russia, this has been manifested in the more frequent occurrence of stationary anticyclones, including those referred to as blocking anticyclones, especially during the summer season. Also, there has been a general increase in regional temperatures during the growing season over the period mentioned above, and combined with the more frequent occurrence of anticyclones has led to less humid conditions. In the Missouri region of the Central USA, variability in the circulation on differing time scales within the Eastern Pacific plays a strong role in the conditions that impact the growing season. As a result of changes in climate and climate variability, the benefit to agriculture during this period produces mixed results for both regions. This work will evaluate the growing season conditions using indexes that combine growing season temperature and precipitation such as the hydrothermal coefficient (HTC) and the bioclimatic potential (BCP). Also, the interannual variability of these indexes in both regions was examined. In the Belgorod region, the increase in temperature combined with little change in precipitation produced mixed results in interpreting these indexes. This was accompanied by more variable conditions as revealed by these indexes in the early twenty-first century. In the Missouri region, there was little trend in either index over the time period and the tendency was toward less climatic variability in the HTC and BCP.
A method for evaluating the penetration of a stable layer by an elevated convective downdraft is discussed. Some controversy exists on the community's ability to define truly elevated convection from surface-based convection. By comparing the downdraft convective inhibition (DCIN) to the downdraft convective available potential energy (DCAPE), we determine that downdraft penetration potential is progressively enabled as the DCIN is progressively smaller than the DCAPE; inversely as DCIN increases over DCAPE, so does the likelihood of purely elevated convection. Serial vertical soundings and accompanying analyses are provided to support this finding.
A 10-year study of elevated severe thunderstorms was performed using The National Centers for Environmental Information Storm Events Database. A total of 80 elevated thunderstorm cases were identified, verified, and divided into "Prolific" and "Marginal" classes. These severe cases occurred at least 80 km away from, and on the cold side of, a surface boundary. The downdraft convective available potential energy (DCAPE), downdraft convective inhibition (DCIN), and their ratio are tools to help estimate the potential for a downdraft to penetrate through the depth of a stable surface layer. The hypothesis is that as the DCIN/DCAPE ratio decreases, there exists enhanced possibility of severe surface winds. Using the initial fields from the Rapid Refresh numerical weather prediction model, datasets of DCIN, DCAPE, and their ratio were created. Mann-Whitney U tests on the Prolific versus Marginal case sets were undertaken to determine if the DCAPE and DCIN values come from different populations for the two different case sets. Results show that the Prolific cases have values of DCIN closer to zero, suggesting the downdraft is able to penetrate to the surface causing severe winds. Thus, comparing DCIN and DCAPE is a viable tool in determining if downdrafts will reach the surface from elevated thunderstorms.
Coastal fronts are commonly found along the East Coast of the United States and can often be associated with intense rainfall and flooding due to elevated convection on the cold side of the boundary. Five heavy rainfall events ([greater to or equal than] 250 mm 24 hr-1) during the fall months along the East Coast were investigated using numerical weather prediction (NWP) models to determine the influence of an upper-level trough/cut-off low, an offshore tropical cyclone, a frontal boundary, and a moisture plume on the intense precipitation. Using experimental NWP simulations, it was determined that the tropical cyclone had an impact on the moisture plume and subsequent location of precipitation due to an associated deformation zone. The tropical cyclone prolonged the events by 6 hours, but inhibited the amount of moisture and resulting precipitation by deterring southeasterly flow. Evaporation from precipitation (surface heat fluxes) contributed to less than 25% (33%) of the precipitation, while latent heat release had the largest impact on the rain totals due to positive feedback from convection and an influence on the frontal boundary. Terrain also impacted the frontal boundary in each event, altering precipitation totals. Parcel trajectories confirmed regions of frontogenesis to be the main source of lift for the release of gravitational instability and convective initiation in each event, while the extratropical cyclone provided upper-level support for ascent and organized the plume of deep tropospheric moisture perpendicular to the front. Three of the five events lasted multiple days due to negative PV advection by the irrotational wind, in response to latent heat release in the region of convection, acting to slow the propagation of the upper-level low.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.